The smka_decode_frame function in libavcodec/smacker.c in FFmpeg before 2.6.5, 2.7.x before 2.7.3, and 2.8.x through 2.8.2 does not verify that the data size is consistent with the number of channels, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted Smacker data.